Rotary piston engine

ABSTRACT

Crown teeth of a driving rotor are received between the spur teeth of an idler rotor which rotates on an offset axis. The respective rotors are disposed in a casing provided with a crescent-shaped baffle disposed between the teeth of the respective rotors where the teeth have clearance due to the offset. Transmission of rotary motion may either be effected by contact between the said teeth or through an external jack shaft. Rotary seals are close to the axes of the respective rotors, anti-friction bearings being close to the plane in which the rotor teeth mesh but radially outside of the seals to minimize the moment arms to which the rotors are subject. The rotary seals are provided with flushing and drainage connections.

United States Patent 1 Gerber Sept. 11, 1973 ROTARY PISTON ENGINE [75] Inventor: Karol Gerber, Cudahy, Wis.

[73] Assignee: Koerper Engineering Associates,

Inc., Brookfield, Wis.

[22] Filed: Apr. 8, 1971 [21] Appl. No.: 132,306

[52] [1.5. CI 418/107, 418/109, 418/142, 418/169, 277/74 [51] Int. Cl. F01c 1/10, F03c 3/00, F040 1/06 [58] Field of Search 418/107-109, 168,169,142,140,170, 171, 166, 19; 277/74 [56] References Cited UNlTED STATES PATENTS 2,044,893 6/1936 Wilhelm et al. 418/169 1,787,543 1/1931 Nichols 418/168 3,214,087 /1965 Luck.... 418/142 1,709,580 4/1929 Jensen 418/169 3,316,851 5/1967 Hagenes 418/169 1,795,040 3/1931 Renfrew 418/169 597,274 1/1898 Engberg 418/107 1,584,207 5/1926 Bell 418/108 1,441,375 1/1923 Rolaff 418/108 es 105 7/6 W II II 56 .ll y

H 11mm 'lllll 2,822,124 2/1958 Klessig et al 418/108 2,902,301 9/1959 Daeschner 277/74 FOREIGN PATENTS OR APPLICATIONS 485,876 5/1938 Great Britain 418/107 Primary ExaminerCarlton R. Croyle Assistant Examiner-John J. Vrablik Attorney-Wheeler, House & Wheeler [57] ABSTRACT Crown teeth of a driving rotor are received between the spur teeth of an idler rotor which rotates on an offset axis. The respective rotors are disposed in a casing provided with a crescent-shaped baffle disposed between the teeth of the respective rotors where the teeth have clearance due to the offset. Transmission of rotary motion may either be effected by contact between the said teeth or through an external jack shaft. Rotary seals are close to the axes of the respective rotors, anti-friction bearings being close to the plane in which the rotor teeth mesh but radially outside of the seals to minimize the moment arms to which the rotors are subject. The rotary seals are provided with flushing and drainage connections.

7 Claims, 11 Drawing Figures 40 ill /6 53 l r- 14a /4 Uma PAIENIEDSEPI nan SHEET 4 UF 4 ROTARY PISTON ENGINE BACKGROUND OF INVENTION As disclosed in US. Pat. No. 3,364,868, it is an important feature for convenience of manufacture of an engine of this type to have all bearing surfaces either flat or cylindrical, the pumping action being effected by volumetric displacement of the liquid pumped and without necessarily requiring sealing contact between the meshing teeth of the driving and driven rotors.

Normally, the bearings for a pump of this character have been located externally of the pump housing with the result that the displacement teeth have to be cantilevered beyond the bearings at considerable sacrifice of strength. An alternative arrangement would suggest that the bearings be located close to the working rotors and to the axes of the shafts, but in that event they would be exposed to leakage and the pump would not then be adapted to handle sugary or abrasive liquids such as are normally regarded as unpumpable in a pump of this general type.

SUMMARYOF INVENTION In the instant device, there are improvements in the interrelated teeth of the pumping heads of the respective rotors. Primarily, however, the invention relates to an arrangement which eliminates the cantilevering of these heads and also eliminates any exposure of the bearings to the liquid pumped, thus enabling the pump to operate successfully on liquids not heretofore regarded as pumpable in a displacement pump. All problems are solved by increasing the radius of the respective rotors close to the pumping heads and providing channels therein for the seals, with anti-friction bearings for the rotors positioned outside of the seals but inside the casing and in close proximity to the pumping heads. Axially spaced sets of roller bearings so located are isolated from the liquid pumped and are not subject to the moments to which they would be subjected by cantilevered shafts. The rotor structures are therefore extremely rigid and capable of maintaining very fine adjustment.

7 Further protection is provided for the rotating parts by provision for the drainage of liquid leakage and the flushing of the seals.

BRIEF DESCRIPTION OF DRAWINGS in section on the line 2-2 of FIG. 5 is a fragmentary detail view on an enlarged scale and in the plane in which these parts are shown in FIG. 2.

FIG. 6 is a fragmentary view taken in section on the line 6-6 of FIG. I.

FIG. 7 is a detail viewtaken in transverse section on the'line 7-7 of FIG..6.

FIG. 8 is a view taken in section approximately in the plane indicated at 8-8 of FIG. 2.

FIG. 9 is a detail view taken on the line 9-9 of FIG. 2.

' FIG. 10 is a view in plan of parts shown in FIG. 9, looking from the plane indicated at l0l0 in FIG. 9.

FIG. 11 shows on a reduced scale an optional external jack shaft connection between the rotors of the pump.

DETAILED DESCRIPTION The drive shaft 14 has an enlarged head 16 to which is bolted a disk-like rotor 18 provided with axially projecting teeth 20 comparable to those of a crown gear. These teeth have exterior circumferential bearing surfaces 22 closely fitted within a generally cylindrical interior bearing surface 24 of the housing casting 26. A portion of the wall of the pump chamber 25 in which the teeth 20 rotate is not concentric with the drive shaft axis 28, being a cylindrical bearing surface 30 which is concentric with the axis 32 of an idler rotor presently to be described.

The chamber 25 is bounded peripherally by the bearing surfaces 22 and 30 and is closed behind the rotor 18 by means of the closure plate 36 encircled by mounting ring 35. The rings 35 and 36 may be preassembled for unitary handlingQThe bolts 34 engage the bearing ring 40 and are threaded into the housing casting 26 to hold the bearing ring and the closure plate mounting ring 35 in position.

Anti-friction bearings 42 with conical races 44 and 46 carry the head portion 16 of shaft 14 from the bearing ring 40 as shown in FIG. 2. These bearings are located at a relatively great radius from the axis 28 in order that they may be close to the pump rotors while allowing clearance for the packing as hereinafter described. At a smaller radius provided by shaft portion 48, there are other bearings 50 confined between conical races 52 and 54. The conical angles of axially spaced bearings 42 and 50 are opposite in order that they will oppose axial displacement in either direction. The unitarily connected rotor 18 and shaft 14 are thereby provided with axially spaced bearing supports which accurately fix the axis and the plane of rotation.

The bearing ring 40 encloses both sets of bearings and is closed by a cover plate 58 having a packing 60 encircling the shaft 14. By removing the cover plate, it

is possible to obtain access to the screws 62 for a'cljusting means including the several wedges 51 which are disposed at" circumferentially spaced points and channeled to bypass the clamping bolts 34 as shown in FIGS. 9 and 10. With the bolts 34 loose, the wedges are adjusted in or out by means of set screws 53, 55 to move the wedges along the correspondingly inclined surfaces 57 of bearing ring 40. If all wedges receive the same adjustment the axial position of ring 40 with respect to ring 26 is adjusted equally about its circumference. If the wedges are adjusted unequally, the plane of ring 40 can be tilted with respect to ring 26, thus to tilt the plane in which the teeth of rotor 18 rotate. Bolts 34 are then tightened to maintain the wedges in adjustment.

Whereas the external bearing surfaces 22 of the crown teeth 20 bear against the concentric interior su r faces 24 of the housing casting 26, the interior cylindrical surfaces 21 of the crown teeth 20 bear against the concentric cylindrical surface 64 of the crescent baffle 66. This is carried by one of the closure plates (in this case the closure plate 65, opposite closure 36).

While the surface 64 of the crescent is concentric with the axis 28 about which the crown teeth 20 rotate, the inner face 68 of the crescent is concentric with the axis 32 upon which the idler rotor head 70 rotates. The bearing surface 68 is at the same radius as the bearing surface 30 of casting 26. The ends of the teeth 72 of the idler rotor 70 are cylindrical and in bearing engagement both with the inner bearing surface 68 of the crescent 66 and with the seal surface 30 of the housing.

The housing 26 is provided with ports 74 and 76 opening to and from the pump chamber 25. Either port may be the inlet and either may be the outlet according to the direction of rotation of the pump rotors 18 and 70.

As hereinafter explained, the connections for flushing the seals and collecting excess drainage therefrom include ducts conveniently arranged to pass through the closure plate 65. The cylindrical surfaces at the ends of the teeth 72 in engagement with the cylindrical surface 30 of the pump housing 26 provide a seal between the ports 74 and 76, the arcuate extent of surface 30 being desirably equal at least to the arcuate spacing between the teeth 72 in order that the seal may continuously be effective. It will be observed that the crown teeth 20 of the rotor 18 do not contact surface 30 of the housing (FIG. 1).

Fluid arriving through one of the ports enters the re spective interdental spaces 78 between the crown teeth and is carried thereby with rotor l8.about the crescent 66, being subsequently expelled into the opposite. port by the entry of one of the teeth 72 of rotor 70 into the respective interdental space 78. Unless the idler 70 is to be driven from rotor 18, it is not necessary that the teeth 72 of the idler contact the crown teeth 20 of rotor 18. However, if there is to be direct transmission of rotary motion, the idler teeth 72 are desirably provided on their opposite faces with bosses 80 which are not necessarily coextensive axially with the teeth 72 but are contoured for engagement with the lateral surfaces 82 of the crown teeth. See FIGS. 1, 6 and 7. The comers 84 at the opposite sides of the bosses 80 permit free movement of the fluid pumped.

The rotor head is mounted on an idler shaft 86 which rotates on axis 32 int: position accurately fixed by bearings 88 and 90 which are comparable to the bearings 42 and 50 which rotatably position the drive shaft 14. The idler shaft 86 has an enlarged head 94 comparable to the head 16 of the drive shaft. It serves a comparable purpose in locating the bearings 88 in axial proximity to the toothed rotors 18 and 70 while at the same time accommodating the seals presently to be described.

The idler rotor 70 is bolted to an enlarged head 94 and centered thereon by hub 98 which, in effect, is a part of the idler, the parts being in bolted unitary connection. Encircling the disk 96 is the annular closure plate 65 which carries the crescent baffle 66, these parts being bolted together as shown in FIG. 2.

If the idler is not to be driven through the meshing crown teeth 20 and spur teeth 72, it may be driven through a jack shaft 100. An example is shown in the modification of FIG. 11, the idler shaft 86 being extended as indicated at 860. A chain or gear 102 drives the jack shaft from the drive shaft 14. A similar chain or gear 104 communicates motion from the jack shaft to the extended idler shaft 860. The drives are dimensioned to give proper ratio to the rotors. The resulting drive involves no contact between the idler and power rotors.

Means is provided for accurate adjustment of the relative positions of the driving rotor. In the instant embodiment, the housing 26 mounted on base 106 provides the fixed surfaces from which the adjustments are effected. At angularly spaced points about the opposite faces of the casting 26, there are axially projecting dowels such as those shown in FIG. 2 at 108 and 110. The respective closure plate mounting rings 35 and 65 have bolt holes 112 which provide radial clearance around bolts 34 to accommodate adjustment of the respective rings. The holes 114 that accommodate the dowels are similarly enlarged with respect to the dowels to provide clearance for adjustment.

Adjustment of the rings 35 and 65 radially of the respective axes is effected by the set screws 116 which extend through the rings into engagement with the dowels. By slightly loosening the appropriate bolts 34 and manipulating the set screws, the respective driving and idler shafts may be adjusted into the desired positions of their respective axes. It is even possible to achieve such fine adjustment that there is no actual contact between the rotors and the walls of the pumping chamber.

THE SEALS FIG. 5 is an enlarged detail view of a portion of FIG. 2 to show a preferred sealing arrangement typical of those which intervene between the large radius bearings of the driving and idler shafts and the respective axes upon which the shafts rotate. It will be observed that the head 16 of the driving shaft 14 is provided with an annular seal channel 1 18 which is encircled by bearings 42. The seal carrier ring 36 has an annular flange 122 extending into the channel 1 l8. Complementary to the flange 122, and likewise disposed within the channel 118 is a ring 124 in nested assembly with ring 126. The dowels 128 and 130 connect the nested rings 124 and 126 to each other and to the driving rotor disk portion 18, from which the crown teeth 20 project. Abutting the ring 126 is an annular seat 132 engaged by the annular seal member 134 which is of channel shape in cross section as clearly shown in FIG. 5. A spring 136 confined between the seat 132 and the seal member 134 urges the seal member axially against a complementary seal member 138 carried by the relatively fixed seal carrier 120.

A second and opposing seal is provided between the ring 138 on the seal carrier and'the complementary ring 140 which abuts the end of the annulus 126 that rotates with the shaft and the driving rotor. An annular spring 142 provides sealing pressure by urging the seal ring 140 axially away from channeled ring 138 which provides the spring seat.

A passage 144 in the seal carrier member 120 carries flushing liquid into that portion 146 of channel 118 in which the seal parts 132 and 126 are disposed. Any fluid escaping from the pumping cavity 25 and getting past seal 132 will be intercepted by the seal 140 and will be flushed from the intervening space by liquid entering through the passage M4, and encircling the channel 118 and leaving through the passage 148.

' If any of these fluids pass the seal 140, they will be intercepted by a conventional seal M3 and drained through the passage 150. Thus the arrangement is adapted to pump fluids under very high pressure without permitting the escape onto the bearing races of abrasive or sticky fluids which might otherwise damage the bearings provided for the rotating parts.

The fluids used for flushing and the passages pro vided for drainage are desirably all handled through the closure plate 65 as best shown in FIGS. 2 and 8. The discharge duct 148 for flushing liquid leaving the seal chamber 146 which is shown at the right in FIG. 2 passes across the casting 26 through the lined duct 149 and then passes upwardly through duct to the discharge pipe 153. As shown in FIG. 2, the duct 155 which comparably leads from the seal shown at the left in FIG. 2 passes into the closure plate 65 which communicates with duct 157 shown in dotted lines in FIG. 8. This duct leads to the discharge pipe 159.

The draining passage 150 shown in FIG. 5 and FIG. 2 communicates through a lined bore 152 in the casting 26 with a duct 154 in the closure plate 65. Duct 154 leads to a drainage discharge pipe 156.

The pipe 158 supplies the flushing liquid for the driving side, being in communication withthe passage 144 shown in FIG. 5. Similarly the pipe 160 supplies flushing liquid for the driven side.

Drainage from the driven side escapes through duct 170 which communicates with the drainage pipe 172 shown in FIG. 8.

TEMPERATURE CONTROL Assuming that cooling (or heating) is required (cooling will normally be the case), liquid such as a coolant can be supplied through pipe 180 which communicates with cavity 182 (FIG. 1). This cavity is the first of an annular series of communicating cavities 186, 188, etc. provided within casting 26 and encircling the pumping chamber 34. These are offset where necessary to pass about the several connecting bolts and dowels and the inlet and outlet ports. In FIG. I, the portion of the cooling circuit which passes the port 76 shown at the left in that view is not illustrated but it is comparable to the duct shown in dotted lines at 184 in a plane to bypass the port 74. The cavities I86 and 188 are connected with each other by a passage not illustrated because it is closer to the observer than the plane in which the section is taken. It is, however, similar to the passage shown at 190 (FIG. 1, upper right) which provides communicationbetween the cavity 184 and the cavity 192 from which the coolant is exhausted through the delivery pipe 194. To maintain their capacity, the respective ports are made shallower and wider where required to provide accommodation for the coolant passages.

with each other or with any fixed surface, there is minimum frictional drag. The idler rotor is not torque loaded. Both rotors have axially spaced sets of tapered roller bearings with pre-load for assured accuracy of operation.

The seals will be noted to have desirably small radius by reason of their location inside of the shaft bearings. Notwithstanding this arrangement, duct means have been provided to pass flushing liquid to and from the seals, if needed. In the preferred organization ducts for flushing liquids and temperature controlling liquids (such as coolants) are desirably provided in a disk or plate which is a separable part of the pump casing.

I claim:

I. In a pump for non-lubricating liquids, said pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the bearings for one rotor being at the opposite side of the chamber from the bearings for the other rotor whereby the teeth of each rotor extend toward each other into said chamber axially beyond their respective support bearings and derive cantilever support therefrom, the improvement for reducing the moment arm of forces exerted on said teeth and said rotor and thence on said bearings and for protecting said bearings from leakage of said liquid from said chamber, said improvement comprising:

a. one of said rotors having a head of large external radius,

b. a bearing radially outwardly of said head and between said head and said casing and in axial'proximity to said cavity to minimize the moment arm of said forces,

0. said head having:

I. a central boss attached to said rotor,

2. an annular packing recess radially outwardly of the' boss and opening toward said chamber to intercept leakage liquid,

3. an annular bearing support ring radially outwardly of said packing recess and overhanging said recess for the support of said bearing,

d. packing in said recess to isolate said bearing from said leakage liquid.

2. In a pump for non-lubricating liquids, said pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the improvement for reducing the moment arm of forces exerted on said teeth and said rotor and thence on said bearings and for protecting said bearings In consequence of the disclosed improvements, this pump may be operated effectively, even at relatively low speeds, to handle even abrasive or non-lubricating liquids. All seals are flushed. Temperatures are controlled by circulation of coolant through cavities and passages provided in the casing. The unique bearing and seal design results in low inertia and in high rigidity of rotating parts. They can be adjusted to minimum clearances and will resist deflection, thus maintaining such clearances. Since the pumping action is effected tating parts can be adjusted to rotate without contact I from leakage of said liquid from said chamber, said improvement comprising one of said rotors having a head of large external radius, a bearing between said head and said casing and in axial proximity to said cavity to minimize the moment arm of said forces, said head having a central boss attached to said rotor, an annular packing recess radially outwardly of the boss and opening toward said chamber to intercept'leakage liquid, an annular bearing support ring radially outwardly of said packing'recess and overhanging said recess for the support of said bearing, packing in said recess to isolate said bearing from said leakage liquid, a flushing duct leading to said packing recess at the side of the packing opposite said chamber, and means for pressurizing said flushing duct at a pressure higher than the leakage liquid, whereby to flush such leakage liquid back into the chamber.

3. The pump of claim 2 in combination with a second packing in said recess at the side of said packing recess opposite said chamber, and a drainage duct from said second packing to drain away any liquid force through said second packing.

4. The pump of claim 2 in which said packing is provided with a seat and a spring which yields when the liquid is pressurized, thus to flush said liquid past said packing.

5. In a pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the bearings for one rotor being at the opposite side of the chamber from the bearings for the other rotor whereby the teeth of each rotor extend toward each other into the chamber axially beyond their respective support bearings and derive cantilever support therefrom, the improvement for adjusting the path of rotation of said teeth within said cavity in which the casing includes a ring for the pumping chamber and an axially adjacent ring against which bearings of one of said rotors seat, and adjusting means for adjusting the axial relationship of said rings and to adjustably tilt the plane of rotation of the teeth of said rotor with respect to the plane of rotation of the teeth of the other rotor.

6. The pump of claim 5 in which said adjusting means comprises a series of cavities about the periphery of the casing and intervening between said axially adjacent rings, said cavities having opposed converging walls, wedges in said cavities and having complementary converging faces, and means for moving said wedges circumferentially to exert axial adjustment pressure against said rings.

7. The pump of claim 5 in further combination with adjusting means for adjusting the radial relationship of said rings. 

1. In a pump for non-lubricating liquids, said pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the bearings for one rotor being at the opposite side of the chamber from the bearings for the other rotor whereby the teeth of each rotor extend toward each other into said chamber axially beyond their respective support bearings and derive cantilever support therefrom, the improvement for reducing the moment arm of forces exerted on said teeth and said rotor and thence on said bearings and for protecting said bearings from leakage of said liquid from said chamber, said improvement comprising: a. one of said rotors having a head of large external radius, b. a bearing radially outwardly of said head and between said head and said casing and in axial proximity to said cavity to minimize the moment arm of said forces, c. said head having:
 1. a central boss attached to said rotor,
 2. an annular packing recess radially outwardly of the boss and opening toward said chamber to intercept leakage liquid,
 3. an annular bearing support ring radially outwardly of said packing recess and overhanging said recess for the support of said bearing, d. packing in said recess to isolate said bearing from said leakage liquid.
 2. In a pump for non-lubricating liquids, said pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the improvement for reducing the moment arm of forces exerted on said teeth and said rotor and thence on said bearings and for protecting said bearings from leakage of said liquid from said chamber, said improvement comprising one of said rotors having a head of large external radius, a bearing between said head and said casing and in axial proximity to said cavity to minimize the moment arm of said forces, said head having a central boss attached to said rotor, an annular packing recess radially outwardly of the boss and opening toward said chamber to intercept leakage liquid, an annular bearing support ring radially outwardly of said packing recess and overhanging said recess for the support of said bearing, packing in said recess to isolate said bearing from said leakage liquid, a flushing duct leading to said packing recess at the side of the packing opposite said chamber, and means for pressurizing said flushing duct at a pressure higher than the leakage liquid, whereby to flush such leakage liquid back into the chamber.
 2. an annular packing recess radially outwardly of the boss and opening toward said chamber to intercept leakage liquid,
 3. an annular bearing support ring radially outwardly of said packing recess and overhanging said recess for the support of said bearing, d. packing in said recess to isolate said bearing from said leakage liquid.
 3. The pump of claim 2 in combination with a second packing in said recess at the side of said packing recess opposite said chamber, and a drainage duct from said second packing to drain away any liquid force through said second packing.
 4. The pump of claim 2 in which said packing is provided with a seat and a spring which yields when the liquid is pressurized, thus to flush said liquid past said packing.
 5. In a pump having a casing with a cavity forming a pumping chamber, rotors with interacting liquid displacing teeth in said chamber and bearings for said rotors outside said chamber, the bearings for one rotor being at the opposite side of the chamber from the bearings for the other rotor whereby the teeth of each rotor extend toward each other into the chamber axially beyond their respective support bearings and derive cantilever support therefrom, the improvement for adjusting the path of rotation of said teeth within said cavity in which the casing includes a ring for the pumping chamber and an axially adjacent ring against which bearings of one of said rotors seat, and adjusting means for adjusting the axial relationship of said rings and to adjustably tilt the plane of rotation of the teeth of said rotor with respect to the plane of rotation of the teeth of the other rotor.
 6. The pump of claim 5 in which said adjusting means comprises a series of cavities about the periphery of the casing and intervening between said axially adjacent rings, said cavities having opposed converging walls, wedges in said cavities and having complementary converging faces, and means for moving said wedges circumferentially to exert axial adjustment pressure against said rings.
 7. The pump of claim 5 in further combination with adjusting means for adjusting the radial relationship of said rings. 